ISOLATION OF A BETA-TUBULIN GENE FROM FUSARIUM-MONILIFORME THAT CONFERS COLD-SENSITIVE BENOMYL RESISTANCE

A beta-tubulin gene from a UV-irradiated benomyl-resistant mutant of F usarium moniliforme was isolated, cloned, and sequenced. The gene enco des a 446-amino-acid polypeptide with homology to other fungal beta-tu bulins. RNA blot analysis showed expression of the gene during vegetat ive growth and conidial germination but no expression during conidiati on. A point mutation, which likely confers benomyl resistance, has bee n identified in the cloned gene; this mutation results in a single ami no acid substitution of asparagine for tyrosine at position 50. Expres sion of benomyl resistance in the mutant was also cold sensitive. Sexu al crosses between the mutant and a mild-type strain indicated cosegre gation of benomyl resistance and cold sensitivity.